/Engine/Plugins/Runtime/GeometryProcessing/Source/DynamicMesh/Public/Parameterization/MeshPlanarSymmetry.h
Tolerances used for matching / hashing in symmetry-findingPoint must be within this distance from the symmetry plane to be considered "on" the plane. Note: Vertices can still be matched below this tolerance; this is just the distance at which a lack of match is considered a lack of symmetry Note: Each Tolerance Factor will be multiplied by "ErrorScale", so that it can appropriately scale up for larger inputs. SetErrorScale() must be called before using these tolerances.
static constexpr double OnPlaneToleranceFactor = (double)FMathf::ZeroTolerance * .5;